RESUMEN
We report a case of a 61-year-old woman with a large atrial septal defect (ASD) that was detected incidentally on chest radiography and computed tomography when she presented with sepsis. Echocardiography confirmed a large secundum ASD with left-to-right shunt flow, right heart dilatation and severe pulmonary hypertension. The patient had a poor clinical outcome despite intensive care and eventually passed away. Haemodynamically significant ASDs have a known association with increased morbidity and mortality, and their early detection and closure cannot be understated. This article aimed to highlight the imaging features of ASD, with special emphasis on the routine chest radiograph. The pathophysiology and clinical manifestations of ASD are also briefly discussed.